scholarly journals Evaluation of the Modal Coupling Effect in Midstory Isolation Systems Based on Random Vibration Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xiao Song ◽  
Songtao Xue
Keyword(s):  
Performance Indicator ◽  
Coupling Effect ◽  
Domain Analysis ◽  
Parameter Analysis ◽  
Mass Ratio ◽  
Isolation System ◽  
Amplification Effect ◽  
Isolation Layer ◽  
Mode Superposition Method ◽  
Depth Analysis

At present, the midstory isolation (MSI) technology has great potential for application in historical buildings’ retrofitting and multifunction buildings. The coupling effect due to the variability of the location of the isolation layer may amplify the structural seismic response and is required for in-depth analysis. This paper aims to evaluate the magnitude of the coupling effect and delimitate the region of the coupling effect to be considered. Based on the complex mode superposition method, the explicit formulas for calculating the random response of the simplified model are deduced. The root-mean-square (RMS) ratio of the shear force coefficient of the upper isolation system is adopted as the performance indicator to evaluate the coupling amplification effect of the MSI system. Parameter analysis indicates that the coupling region is closely related to the mass ratio and frequency ratio of the upper and lower structures to the isolation layer. In general, the region of the coupling effect to be considered can be divided into two parts according to parameters of frequency ratios, depending on the thresholds of the performance indicator. As the mass ratio of the upper isolation system to the entire system increases, one of the coupling regions shrinks and eventually disappears, indicating that the coupling amplification effect in this region can be neglected under certain conditions. Finally, the time-domain analysis of three representative numerical cases of MSI buildings was performed to verify the reliability of the results obtained from the frequency-domain analysis. The research results can provide technical guidance for the preliminary design of the MSI buildings.

Parameter Analysis and Shaking Table Test Based on Mechanics Analysis in Seismic Isolation System of Transformer with Bushings

2013 ◽  
Vol 859 ◽  
pp. 33-42
Author(s):  
Mei Gen Cao ◽  
Juan Mo
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Power Transformer ◽  
Shaking Table ◽  
Parameter Analysis ◽  
Particle Analysis ◽  
Isolation System ◽  
Large Power ◽  
Isolation Layer

Earthquake damage many times in history indicate thatthe destroy type of large power transformer is diverse in earthquake andvulnerability is very high. Isolationtechnology can effectively reduce seismic response of the transformer and bushings,but transformer isolation layer design and parameter selection have a largerimpact on the isolation effect. Firstly, one transformer model installing 220,500kV real bushings for testing and analysis is designed which its structural dimension is closer totrue transformer. Multi-particle analysis model of the transformer withbushings isolation system (TBIS)and the equations of motion are established, and calculationprocedures are compiled using MATLABprogram. Secondly, impacts analysis on equivalent horizontal stiffness and dampingratio of the isolation layer are carried out subjectedto earthquake. Reasonable ranges ofstiffness and damping parameters have been determined. Earthquake simulatortesting of the transformer with real bushings is implement which transformertank filled with water in the test. Acceleration, displacement and stressresponse of transformer and bushings with or without isolation bearings wereobtained. Analysis and experiments show that the rational designing isolationlayer parameters can effectively reduce the seismic response of transformers andbushings. In conclusion, mentioned above research have reference role toseismic isolation design and application for power transformer and bushings forthe future.

An hourglass-type electromagnetic isolator with negative resistance electromagnetic shunt circuit

2020 ◽  
Vol 64 (1-4) ◽  
pp. 549-556
Author(s):  
Yajun Luo ◽  
Linwei Ji ◽  
Yahong Zhang ◽  
Minglong Xu ◽  
Xinong Zhang
Keyword(s):  
Vibration Isolation ◽  
Electromechanical Coupling ◽  
Coupling Effect ◽  
Negative Resistance ◽  
Isolation System ◽  
Amplitude Vibration ◽  
Vibration Responses ◽  
The Stability ◽  
Isolation Performance ◽  
Shunt Circuit

The present work proposed an hourglass-type electromagnetic isolator with negative resistance (NR) shunt circuit to achieve the effective suppression of the micro-amplitude vibration response in various advanced instruments and equipment. By innovatively design of combining the displacement amplifier and the NR electromagnetic shunt circuit, the current new type of vibration isolator not only can effectively solve the problem of micro-amplitude vibration control, but also has significant electromechanical coupling effect, to obtain excellent vibration isolation performance. The design of the isolator and motion relationship is presented firstly. The electromechanical coupling dynamic model of the isolator is also given. Moreover, the optimal design of the NR electromagnetic shunt circuit and the stability analysis of the vibration isolation system are carried out. Finally, the simulation results about the transfer function and vibration responses demonstrated that the isolator has a significant isolation performance.

A Weibull Stress Approach Incorporating the Coupling Effect of Constraint and Plastic Strain in Cleavage Fracture Toughness Predictions

2014 ◽  
Author(s):  
Claudio Ruggieri ◽  
Robert H. Dodds
Keyword(s):  
Fracture Toughness ◽  
Plastic Strain ◽  
Cleavage Fracture ◽  
Coupling Effect ◽  
Crack Size ◽  
Parameter Analysis ◽  
Pressure Vessel Steel ◽  
Fracture Parameter ◽  
Vessel Steel ◽  
Weibull Stress

This work describes a micromechanics methodology based upon a local failure criterion incorporating the strong effects of plastic strain on cleavage fracture coupled with statistics of microcracks. A central objective is to gain some understanding on the role of plastic strain on cleavage fracture by means of a probabilistic fracture parameter and how it contributes to the cleavage failure probability. A parameter analysis is conducted to assess the general effects of plastic strain on fracture toughness correlations for conventional SE(B) specimens with varying crack size over specimen width ratios. Another objetive is to evaluate the effectiveness of the modified Weibull stress (σ̃w) model to correct effects of constraint loss in PCVN specimens which serve to determine the indexing temperature, T0, based on the Master Curve methodology. Fracture toughness testing conducted on an A285 Grade C pressure vessel steel provides the cleavage fracture resistance (Jc) data needed to estimate T0. Very detailed non-linear finite element analyses for 3-D models of plane-sided SE(B) and PCVN specimens provide the evolution of near-tip stress field with increased macroscopic load (in terms of the J-integral) to define the relationship between σ̃w and J. For the tested material, the Weibull stress methodology yields estimates for the reference temperature, T0, from small fracture specimens which are in good agreement with the corresponding estimates derived from testing of much larger crack configurations.

Shaking Table Test Study on Mid-Story Isolation Structures

2012 ◽  
Vol 446-449 ◽  
pp. 378-381
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yu Hong Ma ◽  
Chao Yong Shen
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Natural Period ◽  
Isolation System ◽  
Isolation Layer ◽  
Lead Rubber Bearing ◽  
Complex Structural

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with lead rubber bearing are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.

scholarly journals Inelastic Parametric Analysis of Seismic Responses of Multistorey Bidirectional Eccentric Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-20
Author(s):  
Yu-ping Kuang ◽  
Xin-liang Jiang ◽  
Nan Jiang
Keyword(s):  
Seismic Response ◽  
Parametric Analysis ◽  
Coupling Effect ◽  
Parameter Analysis ◽  
Seismic Responses ◽  
Load Direction ◽  
General Law ◽  
Eccentric Structure ◽  
Natural Frequency Variation ◽  
Elastic Stage

This paper conducts a parametric study on the seismic response of multistorey bidirectional eccentric structures from elastic stage to inelastic stage. Based on a simplified multistorey bidirectional eccentric model composed of bidirectional lateral load-resisting members, a general law is proposed for three-stage natural frequency variation behaviour from elastic stage to inelastic stage of eccentric frame structures with different layers. Different simplification treatments are conducted on each stage and the three stable parameter analysis stages are defined. The corresponding dynamic stiffness matrices and motion equations in different loading stages are derived. On this basis, a parametric analysis of seismic response of a three-storey bidirectional regular eccentric structure from elastic stage to inelastic stage is conducted. Effects of the uncoupled torsion to lateral frequency ratios (Ω) and bidirectional eccentricities on the seismic responses are investigated. The results reveal that as Ω increases, translational displacement in the load direction first decreases and then increases; meanwhile, the displacement perpendicular to load direction and torsion displacement first rise and then decrease sharply. When Ω=1.1, the coupling effect between the translation in the load direction and the torsion is at its strongest condition. Increasing the eccentricities leads to a decrease in the displacement in the load direction as well as an increase in the displacement perpendicular to load direction and torsion displacement. Variation regularity of inelastic seismic response is remarkably different from that in elastic stage. The lateral-torsional coupling effect of the bidirectional eccentric structure is closely related to both the period ratio and the bidirectional eccentricities.

scholarly journals Seismic Fragility Analysis of Mid-Story Isolation Buildings

2021 ◽  
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Near Field ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Plastic State ◽  
Far Field ◽  
Analysis Method ◽  
Isolation System ◽  
Isolation Layer

Abstract. Seismic fragility analysis is essential for seismic risk assessment of structures. This study focuses on the damage probability assessment of the mid-story isolation buildings with different locations of the isolation system. To this end, the performance-based fragility analysis method of the mid-story isolation system is proposed, adopting the maximum story drifts of structures above and below the isolation layer and displacement of the isolation layer as performance indicators. Then, the entire process of the mid-story isolation system, from the initial elastic state to the elastic-plastic state, then to the limit state, is simulated on the basis of the incremental dynamic analysis method. Seismic fragility curves are obtained for mid-story isolation buildings with different locations of the isolation layer, each with fragility curves for near-field and far-field ground motions, respectively. The results indicate that the seismic fragility probability subjected to the near-field ground motions is much greater than those subjected to the far-field ground motions. In addition, with the increase of the location of the isolation layer, the dominant components for the failure of mid-story isolated structures change from superstructure and isolation system to substructure and isolation system.

Vertical Vibration Control of Series Isolation System under Near-Fault Earthquake

2014 ◽  
Vol 638-640 ◽  
pp. 1952-1955
Author(s):  
Q. Rong ◽  
Yan Sheng ◽  
Shi Xin Liu
Keyword(s):  
Seismic Waves ◽  
Damping Ratio ◽  
Vertical Vibration ◽  
Isolation Effect ◽  
Earthquake Intensity ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Isolation Layer ◽  
Near Fault ◽  
Composite Disk

Series isolation system consists of rubber isolation bearings and composite disk springs, determination method of vertical stiffness and vertical damping of isolation layer is given. Entering the near-fault vertical seismic waves, the affect of isolation layer parameters and earthquake intensity on the isolation effect is studied. Studies have shown that the vertical isolation effect increases with the increase of vertical damping ratio. When the damping ratio reaches a certain value, the isolated effect leveles off. When calculating model is adopted as the hierarchical model, vertical isolation effect has nothing to do with the increases of earthquake intensity.

scholarly journals Specific Energy Consumption/Use (SEC) in Energy Management for Improving Energy Efficiency in Industry: Meaning, Usage and Differences

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 247 ◽  
Author(s):  
Akvile Lawrence ◽  
Patrik Thollander ◽  
Mariana Andrei ◽  
Magnus Karlsson
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Specific Energy ◽  
Performance Indicator ◽  
Paper Industry ◽  
Specific Energy Consumption ◽  
Lack Of Information ◽  
Depth Analysis ◽  
Industrial Energy ◽  
Industrial Energy Efficiency

Although several research studies have adopted specific energy consumption (SEC) as an indicator of the progress of improved energy efficiency, publications are scarce on critical assessments when using SEC. Given the increasing importance of monitoring improved industrial energy efficiency and the rising popularity of SEC as an energy key performance indicator (e-KPI), an in-depth analysis and problematization on the pros and cons of using SEC would appear to be needed. The aim of this article is to analyse SEC critically in relation to industrial energy efficiency. By using SEC in the pulp and paper industry as an example, the results of this exploratory study show that although SEC is often used as an e-KPI in industry, the comparison is not always straightforward. Challenges emanate from a lack of information about how SEC is calculated. It is likely that SEC is an optimal e-KPI within the same study, when all deployed SECs are calculated in the same way, and with the same underlying assumptions. However, before comparing SEC with other studies, it is recommended that the assumptions on which calculations are based should be scrutinized in order to ensure the validity of the comparisons. The paper remains an important contribution in addition to the available handbooks.

Mechanism of the Frame-Supported Masonry Shear-Wall Structure with Inter-Story Isolation

2013 ◽  
Vol 351-352 ◽  
pp. 765-770
Author(s):  
Lei Lu ◽  
Ying Zhou
Keyword(s):  
Numerical Analysis ◽  
Shear Wall ◽  
Mixed System ◽  
Wall Structure ◽  
Stiffness Ratio ◽  
Mass Ratio ◽  
Isolation System ◽  
Wall Structures ◽  
Theoretical And Numerical Analysis ◽  
Masonry Shear Wall

Many frame-supported masonry shear-wall structures were observed severely damage in Wenchuan Earthquake. In this paper, an inter-story isolation system is implemented in such structures to mitigate the hazard of the earthquake. The mechanism of the mixed system is demonstrated by theoretical and numerical analysis. And it is concluded that the mass ratio, the below-stiffness ratio, the yield shear of isolated layer and the up-stiffness ratio are the main parameters whose effects are discussed separately. For the design convenience, a set of fitting equations of these parameters are provided.

Study on Isolated Layer Mechanics Character of Combined Base Isolated Structure Based on Axial Forces Redistribute

2012 ◽  
Vol 166-169 ◽  
pp. 627-631 ◽  
Author(s):  
Fu You Zhang ◽  
Ming Gu ◽  
Yun Song ◽  
Song Xu
Keyword(s):  
Axial Force ◽  
Horizontal Displacement ◽  
Vertical Force ◽  
Isolation System ◽  
Isolation Layer ◽  
Calculating Method ◽  
Axial Forces ◽  
Rubber Bearings

Abstract：Combined isolation system is combined with rubber bearings which provide resilience forces and sliding isolated bearings which provide damp. According to the rule of axial forces redistributing between two kinds of bearings under earthquake, a calculating method considering the vertical force redistribute of isolation layer was given. With this method, the results of an example show that axial force will transfer from rubber bearings to sliding isolated bearings along with the horizontal displacement of isolation layer. The bigger the displacement is the more axial force transfers. So the axial-forces redistribution is a self-adjustable performance of the system, and also is an advantage for the system.

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